M-Alkynylanilides and use as herbicides

ABSTRACT

Compounds of the general structural formula, ##STR1## in which R 1  is C 1  to C 4  lower alkyl, cycloalkyl or alkylamino and R 2  is H or lower N-alkylcarbamyl are made from corresponding m-aminophenylacetylenic compounds by conventional methods and are useful as selective herbicides.

This is a division of application Ser. No. 140,645 filed Apr. 16, 1980and now U.S. Pat. No. 4,305,751.

DESCRIPTION OF THE INVENTION

This invention is directed to novel compounds of the structural formula##STR2## in which R¹ is C₁ to C₄ lower alkyl, cycloalkyl or alkylaminoand R² is H or lower N-alkylcarbamyl and use of these compounds asselective herbicides to combat unwanted vegetation. The compounds ofthis invention are particularly useful for control of broadleaf weeds inpeanuts, by either pre- or post-emergent application. The novelherbicides are characterized by high potency with low residual effects.

SYNTHESIS OF THE HERBICIDES

The compounds of this invention are readily synthesized by reaction ofacyl halides with corresponding m-aminophenylacetylenic compounds. Thelatter compounds may be prepared by methods disclosed in U.S. Pat. No.4,139,561. Representative procedures are presented in the followingillustrative examples.

EXAMPLE 1. Preparation of compound No. 755

This is illustrative of preparations wherein both amine and hydroxyfunctions are reacted with isocyanate.

To a 500 ml rb flask equipped with a magnetic stirrer, condenser, and aheating mantle were added 2-methyl-4-(3-aminophenyl) 3-butyn-2-ol (7.0g, 0.040 mole), toluene (200 ml), methylisocyanate (6.8 g, 0.12 mole)and one drop of stannous octanoate. The mixture was brought to refluxfor 2 hours, filtered while warm, and allowed to cool overnight. Thewhite, crystalline product was filtered and dried to give 8.6 g, mp168°-9° C.

EXAMPLE 2. Preparation of compound No. 2499

This is illustrative of preparations wherein only the amine group isreacted with isocyanate.

To a 300 ml rb flask equipped with a magnetic stirrer and a condenserprotected with a drying tube were added2-methyl-4-(3-aminophenyl)-3-butyn-2-ol (8.75 g, 0.050 mole)tetrahydrofuran (100 ml), methylisocyanate (2.90 g, 0.051 mole). Themixture was stirred at room temperature overnight. The solvent wasstripped under reduced pressure to give an oil. Trituration withmethylene chloride produced a white solid, 10.6 g, mp 150-2 d. The solidwas dissolved in warm methanol (50 ml). Water was added until turbid(˜30 ml). Upon cooling white needles formed, 10.0 g. The melting pointremained at 150°-2° C. with gas evolution.

EXAMPLE 3. Preparation of compound No. 760

This is illustrative of preparations wherein the amine function isconverted to an amide.

To a 500 ml Erlenmeyer flask equipped with a magnetic stirrer werecharged 2-methyl-4-(3-aminophenyl)-3-butyn-2-ol (10.0 g, 0.057 mole),tetrahydrofuran (150 ml), and triethylamine (6 ml). Propionyl chloride(6 ml) was added and the mixture was stirred at ambient temperature for30 minutes. After filtration, the filtrate was poured into water (500ml) and extracted with chloroform (3×100 ml). The extracts were driedover magnesium sulfate, filtered, and stripped. The resulting oil wastaken up in 50 mls warm toluene. Upon cooling, crystals were filteredand dried, 9.3 g, mp 155°-6° C.

Below are listed compounds of the above general formula which have beensynthesized by means of the illustrative procedures.

    __________________________________________________________________________    Compound                       Recrystallization                              No.   R.sup.1  R.sup.2   mp °C.                                                                       Solvent                                        __________________________________________________________________________     755  CH.sub.3 NH--                                                                          CH.sub.3 NHCO                                                                           168-169                                                                             toluene                                         760  CH.sub.3 CH.sub.2 --                                                                   H         155-156                                                                             toluene                                        1539  cyclopropyl                                                                            H         171-171.5                                                                           dichloromethane                                1540  (CH.sub.3).sub.3 C--                                                                   H         129.5-130.5                                                                         toluene                                        1547  (CH.sub.3).sub.2 CHNH--                                                                (CH.sub.3).sub.2 CHNHCO--                                                               paste --                                             2499  CH.sub.3 NH--                                                                          H         150-152                                                                             aq. methanol                                   2500  (CH.sub.3).sub.3 CNH--                                                                 H         158-160                                                                             dichloromethane                                __________________________________________________________________________

The elemental analyses for the compounds listed above are as follows:

    ______________________________________                                        Analysis                                                                      Compound Cal.            Found                                                No.      C       H       N     C     H     N                                  ______________________________________                                         755     62.26   6.52    14.52 62.42 6.51  14.02                               760     72.70   7.41    6.06  72.49 7.38  5.85                               1539     74.05   7.04    5.76  74.11 7.20  5.72                               1540     74.10   8.16    5.40  74.79 8.26  5.18                                                              --    --    --                                 2499     67.22   6.94    12.06 66.86 6.64  11.68                              2500     70.04   8.08    10.21 70.73 7.96  9.67                               ______________________________________                                    

A positive identification of molecular structure was obtained by meansof nuclear magnetic resonance spectra. These data for the listedcompounds appear below.

    ______________________________________                                        Nuclear Magnetic Resonance Data                                                               Chemical Shift Relative to                                    No.  Solvent    Tetramethylsilane (δ)                                   ______________________________________                                         755 DMSO--d6   1.62(s,6,C(CH.sub.3).sub.2); 2.4-2.6(overlapping                              doublets,6,NHCH.sub.3); 3.3(s,1,CH.sub.3 NHCOO)                               6.0(s,1,CH.sub.3 NHCON); 6.8-7.7(m,4,ArH);                                    8.6 (s,1, ArNH)                                                760 Acetone--d6                                                                              1.20(t,3,CH.sub.3 CH.sub.2,J = 8); 1.58(s,6,C(CH.sub.3).su                    b.2);                                                                         2.2(q,2,CH.sub.3 CH.sub.2,J = 8); 2.9(s,1,OH);                                4.2(s,1,NH); 7.0-7.8(m,4,ArH)                                 1539 Acetone--d6                                                                              0.6-0.9(m,5,C.sub.3 H.sub.5); 1.53(s,6,C(CH.sub.3).sub.2);                    3.0(s,1,OH); 4.92(s,1,NH); 6.9-7.9                                            (m,4,ArH)                                                     1540 Acetone--d6                                                                              1.30(s,9,C(CH.sub.3).sub.3); 1.56(s,6,C(CH.sub.3).sub.2);                     4.4(bs,1,OH); 6.9-7.9(m,4,ArH);                                               8.6(bs,1,ArNH)                                                2499 Acetone--d6                                                                              1.52(s,6,C(CH.sub.3).sub.2); 3.70(d,3,HNCH.sub.3);                            4.9(s,1,OH); 5.8-6.0(bs,1,HNCH.sub.3);                                        6.8-7.7(m,4,ArH); 8.4(s,1,ArNH)                               2500 Acetone--d6                                                                              1.35(s,9,NC(CH.sub.3).sub.3); 1.52(s,6,C(CH.sub.3).sub.2);                    3.00(s,1,OH); 4.40(s,1,HNC(CH.sub.3).sub.3);                                  6.6-7.7(m,4,ArH); 7.8(s,1,ArH)                                1547 CDCl.sub.3 1.4(d,6,NCH(CH.sub.3).sub.2,J = 7);                                           1.6(d,6,COCH(CH.sub.3).sub.2, J = 7);                                         1.54(s,6,C(CH.sub.3).sub.2); 3.6-4.8(m,4,                                     (CH.sub.3).sub.2 CHNH);                                                       6.8-7.7(m,5,ArH + ArNH)                                       ______________________________________                                    

COMBATING UNWANTED VEGETATION

The novel herbicides are effective when used both post- andpre-emergently. There is described below an illustrative procedure forherbicidal use of the compounds under controlled conditions in thegreenhouse so as to obtain data on phytotoxic activity and selectivity.

(1) Post-Emergent Use

An aqueous dispersion of each active compound was prepared by combining0.4 gram of the compound with about 4 ml of a solvent-emulsifier mixture(3 parts of a commercial polyoxyethylated vegetable oil emulsifier, onepart xylene, one part kerosene) and then adding water, with stirring, toa final volume of 40 ml.

The 24 species of plants on which each compound was to be tested wereplanted in disposable plastic pots in a greenhouse. Ten to eighteen daysafter emergence of the plants, three pots of each species were sprayedat each rate with an aqueous dispersion of the active compound preparedas described above, at rates of both 1 lb and 3 lb of active compoundper acre and at a spray volume of 60 gallons per acre. Approximately oneweek after the spray application the plants were observed and theresults rated according to the following schedule.

DEGREE OF EFFECT

0=no effect

1=slight effect, plants recovered

2=moderate effect, injury to 26 to 75 percent of foliage

3=severe effect, injury to 76 to 99 percent of foliage

4=maximum effect (all plants died)

The same rating schedule was employed to judge pre-emergent resultsobtained according to the procedure below.

(2) Pre-Emergent Use

A solution of each active compound was prepared by dissolving 290 mg ofthe compound to be tested in 200 ml of acetone. Disposable paper traysabout 21/2 inches deep were filled with soil and sprayed with theacetone solution at rates of 3 lb and 1 lb of active chemical per acreof sprayed area, were seeded with 24 species of plant seeds and werethen covered with about 1/4 inch of soil. Twenty-one days after seedingand treatment the plantings were examined and herbicidal effect wasrated.

Results are summarized in the following table.

    __________________________________________________________________________                 Appl'n.                                                                            Compound No.                                                             Rate 755   760   1539  1540  1547  2499   2500                   PLANT SPECIES                                                                              (lb./A.)                                                                           Pre                                                                              Post                                                                             Pre                                                                              Post                                                                             Pre                                                                              Post                                                                             Pre                                                                              Post                                                                             Pre                                                                              Post                                                                             Pre                                                                              Post                                                                              Pre Post               __________________________________________________________________________    Xanthium pensylvanicum                                                                     3    4  4     4  4  4  3  4  4  4  4  4   4   4                  Cocklebur    1    4  4     4  2  4  3  3  3  4  4  4   3   --                 Chenopodium album                                                                          3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Lambsquarters                                                                              1    4  4     4  4  4  3  4  4  4  4  4   4   4                  Ipomoea purpurea                                                                           3    3  4     4  4  4  4  4  3  4  4  4   4   4                  Morning Glory                                                                              1    2  3     2  2  4  4  4  4  4  3  4   2   2                  Amaranthus retroflexus                                                                     3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Pigweed      1    4  3     4  4  4  3  4  2  4  4  4   4   4                  Polygonum convolvulus                                                                      3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Wild Buckwheat                                                                             1    4  4     4  4  4  3  4  3  4  4  4   4   4                  Brassica kaber                                                                             3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Wild Mustard 1    4  4     4  4  4  4  4  1  4  4  4   4   4                  Echinochloa crusgalli                                                                      3    4  4     1  4  3  3  2  4  3  4  4   4   4                  Barnyard Grass                                                                             1    3  2     1  3  3  3  1  3  1  4  4   4   4                  Digitaria sanguinalis                                                                      3    3  3     1  1  2  2  2  2  1  4  4   4   4                  Crabgrass    1    0  0     0  0  1  0  1  0  0  3  4   4   4                  Bromus tectorum                                                                            3    3  3     2  0  2  1  2  1  2  4  4   4   4                  Downy Brome  1    1  0     0  0  1  0  0  0  0  3  4   2   3                  Setaria faberii                                                                            3    4  4     2  2  2  3  3  2  2  4  4   4   4                  Giant Foxtail                                                                              1    1  1     0  1  3  0  2  1  1  3  4   2   3                  Setaria viridis                                                                            3    4  4     4  4  4  4  4  4  3  4  4   4   4                  Green Foxtail                                                                              1    4  3     3  2  3  2  2  2  1  4  4   4   4                  Cyperus esculentis                                                                         3    0  0     0  0  0  0  0  0  0  1  1   1   1                  Nutsedge     1    0  0     0  0  0  0  0  0  0  0  0   0   0                  Sorghum bicolor                                                                            3    4  3     0  3  2  3  3  3  2  3  3   4   3                  Shatter Cane 1    2  1     0  2  3  3  1  2  0  3  3   3   3                  Avena fatua  3    4  4     4  4  3  3  3  4  4  4  4   4   4                  Wild Oats    1    4  4     1  3  2  1  2  2  2  4  4   4   4                  Medicago sativa                                                                            3    4  4     4  4  4  3  4  3  4  4  4   4   4                  Alfalfa      1    1  4     3  1  4  1  2  0  2  4  4   4   4                  Gossypium herbaceum                                                                        3    3  4     3  2  4  4  4  3  4  4  4   4   4                  Cotton       1    1  2     2  1  3  1  4  0  2  2  4   1   4                  Arachis hypogaea                                                                           3    2  3     3  0  1  1  2  0  3  1  3   1   --                 Peanut       1    0  1     1  0  1  0  1  0  1  0  3   0   1                  Soja max     3    4  4     4  4  4  3  3  4  2  4  4   4   4                  Soybean      1    4  3     3  3  3  1  2  3  2  4  4   3   4                  Beta vulgaris                                                                              3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Sugar Beets  1    4  4     4  4  4  4  4  2  4  4  4   4   4                  Lycopersicum esculentum                                                                    3    4  4     4  4  4  4  4  4  4  4  4   4   4                  Tomato       1    4  4     4  4  4  4  4  3  4  4  4   4   4                  Zea mays     3    3  1     0  4  3  3  2  3  2  4  4   4   4                  Corn         1    2  1     0  3  3  2  1  3  0  4  3   4   3                  Sorghum vulgare                                                                            3    4  3     0  3  2  3  2  4  2  4  4   4   4                  Grain Sorghum                                                                              1    2  1     0  2  3  3  1  2  0  3  3   4   3                  Oryza sativa 3    4  4     2  -- -- -- -- -- -- 3  4   3   4                  Rice         1    4  4     1  2  -- -- -- -- -- 3  4   3   4                  Triticum aestivum                                                                          3    4  4     3  4  3  4  3  3  3  4  4   4   4                  Wheat        1    4  3     2  2  2  3  2  3  1  4  4   4   4                  __________________________________________________________________________

The information presented in tabular form herein will enable a worker inthe art to make a selection from among the herbicidal compounds of theinvention and to make some judgment with regard to application rates,depending upon the species which it is desired to control.

The compounds are usually applied in combination with inert carriers ordiluents, as in aqueous sprays, granules and dust formulations inaccordance with established practice in the art. An aqueous spray isusually prepared by mixing a wettable powder or emulsifiable concentrateformulation of a herbicide with a relatively large amount of water toform a dispersion.

Wettable powders comprise intimate, finely divided mixtures of activecompounds, inert solid carriers and surface active agents. The inertsolid carrier is usually chosen from among the attapulgite clays, thekaolin clays, the montmorillonite clays, the diatomaceous earths, finelydivided silica and purified silicates. Effective surfactants, which havewetting, penetrating and dispersing ability are usually present in awettable powder formulation in proportions of from 0.5 to about 10percent by weight. Among the surface active agents commonly used forthis purpose are the sulfonated lignins, naphthalenesulfonates andcondensed naphthalenesulfonates, alkylbenzenesulfonates, alkyl sulfatesand non-ionic surfactants such as products of condensation of ethyleneoxide with alkylphenols.

Emulsifiable concentrates of the herbicidal compounds comprise in eachinstance, a solution of active compound in a liquid carrier which is amixture of water-immiscible solvent and surfactants, includingemulsifiers. Useful solvents include aromatic hydrocarbon solvents suchas the xylenes, alkylnaphthalenes, petroleum distillates, terpenesolvents, ether-alcohols and organic ester solvents. Suitableemulsifiers, dispersing and wetting agents may be selected from the sameclasses of products which are employed in formulating wettable powders.

In general, the herbicidal compounds are applied in formulations whichdesirably contain from 0.1 percent to 95 percent by weight of a compoundof formula (1) and from 0.1 to 75 percent by weight of a carrier orsurfactant.

When a compound is to be applied to the soil, as for a pre-emergenceapplication, granular formulations are sometimes more convenient thansprays. A typical granular formulation comprises the active compounddispersed on an inert carrier such as coarsely ground clay, or claywhich has been converted to granules by treatment of a rolling bed ofthe powdered material with a small amount of liquid in a granulatingdrum. In the usual process for preparing granular formulations, asolution of the active compound is sprayed on the granules while theyare being agitated in a suitable mixing apparatus, after which thegranules are dried with a current of air during continued agitation.

I claim:
 1. Compounds having the general structural formula ##STR3## inwhich R¹ is C₁ to C₄ lower alkyl, cycloalkyl and R² is H.
 2. Anagricultural composition comprising from 0.1 percent to 95 percent byweight of a compound of claim 1 and from 0.1 to 75 percent by weight ofa carrier or surfactant.
 3. The method of combating unwanted vegetationcomprising applying to said vegetation either pre- or post-emergently aneffective amount of a compound of claim 1 in combination with an inertcarrier.
 4. The method of claim 3 in which unwanted vegetation iscombated in the presence of peanuts.
 5. The compound of claim 1 in whichR¹ is ethyl and R² is hydrogen.
 6. The compound of claim 1 in which R¹is cyclopropyl and R² is hydrogen.
 7. The compound of claim 1 in whichR¹ is tert. butyl and R² is hydrogen.